Microelectronic devices are used in a wide array of products. These devices, such as memory and microprocessor chips and similar devices have traditionally been used in, for example, computers, telephones, sound equipment and other electronic products. Over the last several years, microelectronic devices have become faster, better, and less expensive. Microelectronic devices are accordingly now also used in traditionally non-electronic products, such as appliances, vehicles, toys and games, medical devices, novelty items, etc. The remarkable progress made in the microelectronic device industry has led to better yet less expensive products of all types. It has also led to entirely new types of products.
A major factor in the development of microelectronic devices has been the machines and methods used to manufacture them. Manufacturing of microelectronic devices requires extreme precision, extremely pure materials, and an extremely clean manufacturing environment. Even tiny particles of dust, dirt, metals, or manufacturing chemicals, at almost any stage of the manufacturing process, can cause defects and failures in devices. Reducing contaminants is therefore critical to cost effective manufacturing. Accordingly, intensive research and development has focused on reducing contaminants in microelectronic manufacturing processes. As microelectronic devices are made even smaller, reducing contaminants has become even more important, and more difficult to achieve. In the past, various approaches have been used to reduce contaminants. These include use of materials that tend not to generate particles, careful selection and placement of mechanical components in processing machines, and use of a flow of highly filtered and clean air or gases, to carry any particles generated away from the wafers or substrates which form the microelectronic devices. Even though these techniques have been successful, engineering challenges remain in trying to further reduce contamination, to provide more reliable and cost effective manufacturing. As described below, the inventors of this patent application have now designed new machines and methods which offer significantly improved manufacturing of microelectronic devices.
Manufacturing of microelectronic devices involves using various chemicals. These chemicals are typically in liquid form, although gases and vapors are also often used. These chemicals must be highly pure and are therefore expensive. Chemicals used in some processes, such as strong acids or oxidizers, are also toxic. Use and disposal of these chemicals after they are used, can be time consuming and expensive. Consequently, reducing the amount of chemicals used is highly advantageous. On the other hand, in general, enough of the chemicals must be provided so that they can be uniformly applied over all surfaces of the wafer or substrate being processed or manufactured. It can therefore be difficult to minimize chemical consumption, while maintaining good manufacturing results.
Manufacturing microelectronic devices also uses large amounts of purified and de-ionized water. After it is used, e.g., for rinsing, the water typically will have small amounts of dissolved chemicals in it. The water then also often requires special handling and disposal efforts. Accordingly, reducing the amount of water used, as well as the amounts of chemicals used, would be highly advantageous.
Another problem that may occur in existing microelectronic device manufacturing systems is that processing chemicals may be mixed with one another when the chemicals are drained from the processing chamber, and/or when the chemicals are re-circulated back to the processing chamber. When processing chemicals are mixed with one another, disposal of them can be more difficult. Thus, there is a need for a wafer processing system that can effectively isolate different processing chemistries from one another during and after wafer or substrate processing.
Another problem in existing wafer-processing systems arises when a nozzle or other fluid outlet is oriented to spray processing fluid downward onto a wafer. After the fluid delivery is stopped, some excess processing fluid may drip out of the nozzle onto the wafer. At certain times, even a few drops of excess fluid can result in defects or failure of the microelectronic end products. Thus, there is a need for a wafer processing system that overcomes these disadvantages.